The electroless coating of objects is well known. It is also well known in the art that the plating of metal layers can improve the retention of diamond particles in the matrices of cutting tools, such as those used to saw stone and concrete, and grinding tools, such as metal bond wheels. Metal plated particulate material, including natural or synthetic diamonds, are commercially available with nickel coatings typically applied by electroless deposition. While such coated particulate materials provide good performance, improvements are desired to reduce the premature loss of particles and reduce the wear of cutting tools.
While it is known that plating metal layers applied by electroless deposition chemically bind to the surface of particulate matter, other metals which adhere to and form metal layers on the particulate surfaces more strongly include molybdenum, titanium and chromium. These metals are carbide formers and are typically chemically vapor-deposited or sputtered onto particulate surfaces.
These carbide forming metal layers have been used as part of multi-layer coatings on diamond particles to aid retention within a tool matrix. This alloy layer may be over coated with another layer such as nickel by electroless or electrolytic deposition. The alloys comprise at most 30 wt % of the carbide forming metal and, to form the carbide, the coating is heated at high temperatures after deposition by vacuum evaporation or sputtering. These procedures for applying multi-layer coatings are complex in that either metal alloys are applied as one of the layers, or three distinct layers are used. In addition, these procedures provide increased bonding strength between the diamond particles and the tool matrix through carburization of the metal coating, during which the diamond particles are exposed to high temperatures. High temperatures can cause degradation of the diamond crystal, which is detrimental to the performance of the cutting tool.
Notwithstanding the state of the art as described herein, there is a need for an electroless plating bath composition that plates at least one metal layer onto particulate matter by a simpler method which will aid its retention within the matrix of a cutting and grinding tools and improve the tool wear resistance.